Acoustic echo cancellation (AEC) is widely used in teleconference systems. Array microphones are becoming more popular with advances in audio technology. When AEC is applied to array microphones, either an adaptive filter is applied for each microphone in the array, or one adaptive filter is used at the output of the entire array. Adaptive filters require high computation power, and when the number of microphones in the array is large, the processing requirements for AEC can be prohibitively high to accommodate the one adaptive filter per microphone approach.
In order to pick up sound sources from different locations in the room, an array microphone has to dynamically change its beam steering angle. If only one adaptive filter is used for the output of an array microphone, then the adaptive filter adapted for the previous steering angle will not be able to perform AEC well for the current angle. When there is a large difference between the previous steering angle and the current steering angle, the adaptive filter may add more echo instead of cancelling it, or the filter may even become unstable.